Field of the Invention
The present invention relates to a suction cup.
Description of the Prior Art
A suction cup is disclosed in Taiwan Patent No. I604134, including a suction member, a check valve which is disposed in the suction member, an exterior cover unit which is connected to the suction member and a manual exhaust valve which is disposed in the exterior cover unit. The suction member includes a protrusive seat and an gas storage chamber, and the check valve is disposed within a valve hole of the protrusive seat and allows gas to be released from the gas storage chamber to an outside of the protrusive seat. The exterior cover unit includes a gas storage space which is communicated with the gas storage chamber and an outlet channel which is communicated with an outside of the suction cup through the gas storage space. The manual exhaust valve can change a state of the outlet channel from close to open. A pressing member of the manual exhaust valve has an airtight ring sleeved thereon and an indicating segment. The airtight ring is movable relative to the pressing member or the airtight ring is deformable so that the airtight ring can unseal or seal the outlet channel by operating the pressing member. The indicating segment is located in the suction member when air pressure inside the suction cup is lower than the outside of the suction cup, and the indicating segment is gradually revealed out of the suction member when the air pressure inside the suction cup is increased so that a user can identify the level of vacuum inside the suction cup. The suction cup further includes a spring which is elastically abutted against and between the pressing member and the exterior cover unit.
A conventional airtight ring should be deformable for exhaust so that the conventional airtight ring should not be too thick or too hard. However, the airtight ring has to bear elastic force of the spring. Although the pressure inside the suction cup is lower than the outside of the suction cup (for example, a pressure is 0.533 bar), the airtight ring is pushed and moved by the elastic force of the spring and the indicating segment is revealed out of the suction member, which results in erroneous observation.
The present invention is, therefore, arisen to obviate or at least mitigate the above-mentioned disadvantages.